Brief Answer: Orthostatic hypotension likely Detailed Answer: Dear patient, Thanks a lot for your query. I am sorry for the difficult times you are enduring. With cancer patients, given the progressive course of disease, the most common cause of lightheadedness is orthostatic hypotension, meaning a drop in the blood pressure when you change body positions (for example from sitting to standing up), many times exacerbated by poor appetite and lack of fluid intake, along with the nausea and side effects from chemo. It is relatively easy to check for orthostatic hypotension, your nurse or provider can take a set of blood pressures while you lay down, then while you sit and finally after you stand up. If that is not the case, then other possibilities for lightheadedness should be considered, such as low blood sugar from liver dysfunction, heart arrhythmias, etc. Hope this is helpful, wish you the best, Dr Brenes-Salazar MD Mayo Clinic MN

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